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Yi-Hong Wang

1984 B.S. (Plant Breeding) Nanjing Agricultural University, China

1992 M.S. (Plant Breeding) University of the Philippines, Philippines

1999 Ph.D. (Genetics) Clemson University, Clemson, SC, USA

The earth receives approximately 9000 times as much energy from the sun as all human energy needs. Although solar energy can be harvested through wind turbines, solar panel, and sterling engines, the only form of renewable solar energy capture that can contribute substantially to our energy needs at costs competitive with fossil fuel is that harvested by photosynthesis and stored in cellulosic biomass such as agricultural residues, forestry wastes, and energy crops (Science 312:1277). Cellulosic biofuels from biomass thus offer an extremely attractive alternative to fossil fuel because cellulosic biomass is renewable and domestically abundant. But cellulosic biomass is made up of the complex structures of cellulose, hemicellulose, and lignin in the form of plant cell wall which is highly recalcitrant to bioconversion of its carbohydrates into biofuels---a process called saccharification. The latter drives up the cost of cellulosic biofuel production. Therefore, maximizing saccharification yield is essential for cellulosic biofuel to be competitive and is a bottle-neck in cellulosic biofuel production. And improving total biofuel production involves increases in both biomass (determined by height and maturity) and saccharification yield.

Sorghum is a very efficient cellusic biomass producer under warm conditions and is a potential energy crop for the south-central US. Using a pool-based association mapping method adapted from human genetic studies, we have mapped plant height, maturity and saccharification yield using an association panel of >200 sorghum varieties developed at the International Crops Research Institute for the Semi-Arid Tropics (ICRISAT), in collaboration with Dr. Hari Upadhyaya at ICRISAT, with 700 simple sequence repeat (SSR) markers. The markers were detected and analyzed with a LabChip® 90 system that can automatically process about 400 samples in eight hours. The positions of the markers linked to the three traits colocalize with those previously mapped by other groups in sorghum and maize. This confirms the utility of the pool-based association mapping in plants and provides candidate genes for functional characterization in sorghum and Arabidopsis. The current plan is the high-resolution mapping of these traits with 4,000 SSRs which should generate more candidate genes with greater precision.